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Senior Fullstack Engineer, React/Kotlin

Jobtailor

Berlin, State of Berlin, Germany

16 September 2026

Design, build, and maintain scalable customer-facing applications using React and TypeScript Develop and evolve reliable backend services and APIs using Kotlin Contribute to React Native mobile experiences when needed Own features and technical initiatives from problem definition and design through development, testing, deployment, and production support Build experiences that improve merchant and offer discovery, purchasing decisions, and checkout journeys Translate complex or ambiguous product requirements into clear technical solutions and incremental delivery plans Collaborate with Product, Design, Analytics, and Engineering teams across multiple technical domains Design systems with scalability, availability, performance, maintainability, and cost efficiency in mind Implement automated testing, observability, performance monitoring, and safe deployment strategies Troubleshoot production issues and participate in on-call responsibilities Communicate technical decisions, dependencies, risks, tradeoffs, and delivery progress clearly with technical and non-technical stakeholders Participate in design and code reviews, technical documentation, mentoring, and continuous improvement of engineering practices Requirements 5–8 years of professional software engineering experience, including experience building and operating customer-facing products in production Advanced experience developing modern web applications with React and TypeScript Strong understanding of frontend component architecture, state management, automated testing, performance, and accessibility Professional experience designing and developing backend services using Kotlin Experience designing APIs, data models, asynchronous workflows, and service-to-service integrations Working knowledge of React Native and patterns for delivering consistent mobile experiences Experience designing service-oriented or distributed systems with scalability, availability, low latency, maintainability, and cost efficiency in mind Experience with automated testing, observability, production debugging, and progressive deployment strategies Experience supporting and operating production systems, including participation in on-call rotations Demonstrated ability to take ownership of initiatives across the full software development lifecycle Strong communication skills and experience collaborating with distributed, cross-functional teams Ability to work effectively with US-based clients and stakeholders Strong product mindset with the ability to connect technical decisions to customer experience and measurable business outcomes Ability to navigate ambiguity, evaluate technical tradeoffs, and turn broad requirements into practical solutions Experience with Python Experience with experimentation or A/B testing platforms Experience building high-traffic e-commerce, marketplace, shopping, or fintech applications Experience working on systems involving offers, promotions, payments, or transaction workflows Experience mentoring engineers and helping improve engineering standards across a team Core Competencies Demonstrates expertise in building scalable customer-facing applications using React and TypeScript, while also developing reliable backend services with Kotlin. Strong ability to translate complex product requirements into technical solutions and effectively communicate with cross-functional teams. Highest-signal resume keywords React Application Development TypeScript Proficiency Kotlin Backend Development Automated Testing Implementation Cross-Functional Collaboration ATS Optimization Keywords Hard Skills React TypeScript Kotlin API Design Automated Testing Performance Monitoring React Native Python Service-Oriented Architecture E-Commerce Application Development Soft Skills Strong Communication Skills Problem-Solving Mentoring Industry Keywords Customer-Facing Products Scalability Availability Low Latency Transaction Workflows Tools & Technologies A/B Testing Platforms Observability Tools Production Debugging Tools #J-18808-Ljbffr